The present study is the further development of a program of research designed to reduce the onset and extent of drinking and contribute to the changing campus norms through implementation of efficacious Parent-Based Interventions (PBIs) based on the work of Turrisi and colleagues (1999;2000;2001). The focus is on influencing drinking behavior of the students through an intervention with their parents during their first year of college. The conversations will take place in one of three conditions;(1) prior to college matriculation during the transition period between high school and college (PCM), (2) Prior to college matriculation and then throughout the fall semester resulting from booster parent "check-ins" (PCMB), or (3) after college matriculation during the fall of the first semester at college (AMC). All efforts will attempt to make students more resistant to influences that encourage the adoption or continuation of heavy drinking behaviors and reduce these behaviors. Our prior research has provided empirical evidence demonstrating the efficacy of the PCM to warrant an examination of its efficacy as an after matriculation intervention. Although there have been positive reports of efficacy of involvement of parent efforts (e.g., Elliot, 2000), virtually no systematic theory-driven research examining efficacy has been published in the peer review literature exploring whether there is a critical period for implementing parent interventions with college students. This void, coupled with an increased number of universities seeking to involve parents before and after matriculation, argues for systematic empirical efforts. Toward this end the aims can be summarized as follows: (1) To investigate and compare the efficacy of PBIs when administered prior to matriculation versus prior to matriculation with boosters versus after matriculation, (2) To identify subgroups for whom the different PBIs are more effective versus less effective, and (3) To examine mediational processes by which the different PBIs influence alcohol use and consequences.